Powertrain overspeed protection

Abstract

A method of inhibiting an overspeed condition in a vehicle powertrain includes monitoring at least one of an engine speed and a transmission input shaft speed of a torque converter that transfers drive torque between an engine and a transmission and determining an operating condition of the vehicle powertrain. The method further includes determining a first threshold speed based on the operating condition and reducing an engine torque request when the at least one of the engine speed and the transmission input shaft speed exceeds the first threshold speed.

1. An overspeed protection control system that inhibits an overspeed condition in a vehicle powertrain, comprising:
 a first module that monitors at least one of an engine speed and a transmission input shaft speed; 
 a second module that determines a transmission operating condition of said vehicle powertrain; 
 a third module that determines a first threshold speed based on said transmission operating condition; and 
 a fourth module that reduces an engine torque request when said at least one of said engine speed and said transmission input shaft speed exceeds said first threshold speed. 
 
     
     
       2. The overspeed protection control system of  claim 1  wherein said fourth module provides a fixed torque reduction amount, and reduces said engine torque request by said fixed torque reduction amount. 
     
     
       3. An overspeed protection control system that inhibits an overspeed condition in a vehicle powertrain, comprising:
 a first module that monitors at least one of an engine speed and a transmission input shaft speed; 
 a second module that determines an operating condition of said vehicle powertrain; 
 a third module that determines a first threshold speed based on said operating condition; and 
 a fourth module that reduces an engine torque request when said at least one of said engine speed and said transmission input shaft speed exceeds said first threshold speed, 
 wherein said fourth module determines a torque reduction amount based on a difference between said at least one of said engine speed and said transmission input shaft speed and said first threshold speed, and reduces said engine torque request by said torque reduction amount. 
 
     
     
       4. The overspeed protection control system of  claim 1  wherein said third module determines a second threshold speed based on said transmission operating condition and determines said engine torque request without a reduction when said at least one of said engine speed and said transmission input shaft speed is less than said second threshold speed. 
     
     
       5. The overspeed protection control system of  claim 1  wherein said third module determines said first threshold speed based on one of an attained gear speed, a commanded gear speed and a commanded speed profile. 
     
     
       6. An overspeed protection control system that inhibits an overspeed condition in a vehicle powertrain, comprising:
 a first module that monitors at least one of an engine speed and a transmission input shaft speed; 
 a second module that determines an operating condition of said vehicle powertrain: 
 a third module that determines a first threshold speed based on said operating condition; and 
 a fourth module that reduces an engine torque request when said at least one of said engine speed and said transmission input shaft speed exceeds said first threshold speed, 
 wherein said third module determines said first threshold speed based on one of an attained gear speed, a commanded gear speed and a commanded speed profile and 
 wherein said operating condition is one of an upshift and a downshift of a gear ratio of said transmission. 
 
     
     
       7. An overspeed protection control system that inhibits an overspeed condition in a vehicle powertrain, comprising:
 a first module that monitors at least one of an engine speed and a transmission input shaft speed; 
 a second module that determines an operating condition of said vehicle powertrain; 
 a third module that determines a first threshold speed based on said operating condition; and 
 a fourth module that reduces an engine torque request when said at least one of said engine speed and said transmission input shaft speed exceeds said first threshold speed, 
 wherein said operating condition is one of a garage shift condition and a neutral idle condition and said first threshold speed corresponds to a maximum engine speed limit. 
 
     
     
       8. The overspeed protection control system of  claim 1  wherein said transmission is one of an automatic transmission and a continuously variable transmission. 
     
     
       9. A method of inhibiting an overspeed condition in a vehicle powertrain, comprising:
 monitoring at least one of an engine speed and a transmission input shaft speed; 
 determining a transmission operating condition of said vehicle powertrain; 
 determining a first threshold speed based on said transmission operating condition; and 
 reducing an engine torque request when said at least one of said engine speed and said transmission input shaft speed exceeds said first threshold speed. 
 
     
     
       10. The method of  claim 9  further comprising providing a fixed torque reduction amount, wherein said engine torque request is reduced by said fixed torque reduction amount. 
     
     
       11. A method of inhibiting an overspeed condition in a vehicle powertrain, comprising:
 monitoring at least one of an engine speed and a transmission input shaft speed; 
 determining an operating condition of said vehicle powertrain; 
 determining a first threshold speed based on said transmission operating condition; 
 reducing an engine torque request when said at least one of said engine speed and said transmission input shaft speed exceeds said first threshold speed; and 
 determining a torque reduction amount based on a difference between said at least one of said engine speed and said transmission input shaft speed and said first threshold speed, wherein said engine torque request is reduced by said torque reduction amount. 
 
     
     
       12. The method of  claim 9  further comprising:
 determining a second threshold speed based on said transmission operating condition; and 
 determining said engine torque request without a reduction when said at least one of said engine speed and said transmission input shaft speed is less than said second threshold speed. 
 
     
     
       13. The method of  claim 9  wherein said first threshold speed is determined based on one of an attained gear speed, a commanded gear speed and a commanded speed profile. 
     
     
       14. A method of inhibiting an overspeed condition in a vehicle powertrain, comprising:
 monitoring at least one of an engine speed and a transmission input shaft speed; 
 determining an transmission operating condition of said vehicle powertrain; 
 determining a first threshold speed based on said transmission operating condition; and 
 reducing an engine torque request when said at least one of said engine speed and said transmission input shaft speed exceeds said first threshold speed, 
 wherein said first threshold speed is determined based on one of an attained gear speed, a commanded gear speed and a commanded speed profile, and 
 wherein said operating condition is one of an upshift and a downshift of a gear ratio of said transmission. 
 
     
     
       15. A method of inhibiting an overspeed condition in a vehicle powertrain, comprising:
 monitoring at least one of an engine speed and a transmission input shaft speed; 
 determining an transmission operating condition of said vehicle powertrain; 
 determining a first threshold speed based on said transmission operating condition; and 
 reducing an engine torque request when said at least one of said engine speed and said transmission input shaft speed exceeds said first threshold speed, 
 wherein said operating condition is one of a garage shift condition and a neutral idle condition and said first threshold speed corresponds to a maximum engine speed limit. 
 
     
     
       16. The method of  claim 9  wherein said transmission is one of an automatic transmission and a continuously variable transmission. 
     
     
       17. A method of inhibiting an overspeed condition in a vehicle powertrain, comprising:
 monitoring at least one of an engine speed and a transmission input shaft speed; 
 determining a transmission operating condition of said vehicle powertrain; 
 determining a first and second threshold speeds based on said transmission operating condition; 
 reducing an engine torque request when said at least one of said engine speed and said transmission input shaft speed exceeds said first threshold speed; and 
 determining said engine torque request without a reduction when said at least one of said engine speed and said transmission input shaft speed is less than said second threshold speed. 
 
     
     
       18. The method of  claim 17  further comprising providing a fixed torque reduction amount, wherein said engine torque request is reduced by said fixed torque reduction amount. 
     
     
       19. A method of inhibiting an overspeed condition in a vehicle powertrain, comprising:
 monitoring at least one of an engine speed and a transmission input shaft speed; 
 determining an operating condition of said vehicle powertrain; 
 determining a first and second threshold speeds based on said operating condition; 
 reducing an engine torque request when said at least one of said engine speed and said transmission input shaft speed exceeds said first threshold speed; 
 determining said engine torque request without a reduction when said at least one of said engine speed and said transmission input shaft speed is less than said second threshold speed; and 
 determining a torque reduction amount based on a difference between said at least one of said engine speed and said transmission input shaft speed and said first threshold speed, wherein said engine torque request is reduced by said torque reduction amount. 
 
     
     
       20. The method of  claim 17  wherein said first threshold speed is determined based on one of an attained gear speed, a commanded gear speed and a commanded speed profile. 
     
     
       21. A method of inhibiting an overspeed condition in a vehicle powertrain, comprising:
 monitoring at least one of an engine speed and a transmission input shaft speed; 
 determining an operating condition of said vehicle powertrain; 
 determining a first and second threshold speeds based on said operating condition; 
 reducing an engine torque request when said at least one of said engine speed and said transmission input shaft speed exceeds said first threshold speed; and 
 determining said engine torque request without a reduction when said at least one of said engine speed and said transmission input shaft speed is less than said second threshold speed, 
 wherein said first threshold speed is determined based on one of an attained gear speed, a commanded gear speed and a commanded speed profile, and 
 wherein said operating condition is one of an upshift and a downshift of a gear ratio of said transmission. 
 
     
     
       22. A method of inhibiting an overspeed condition in a vehicle powertrain, comprising:
 monitoring at least one of an engine speed and a transmission input shaft speed; 
 determining an operating condition of said vehicle powertrain; 
 determining a first and second threshold speeds based on said operating condition; 
 reducing an engine torque request when said at least one of said engine speed and said transmission input shaft speed exceeds said first threshold speed; and 
 determining said engine torque request without a reduction when said at least one of said engine speed and said transmission input shaft speed is less than said second threshold speed, 
 wherein said operating condition is one of a garage shift condition and a neutral idle condition and said first threshold speed corresponds to a maximum engine speed limit. 
 
     
     
       23. The method of  claim 17  wherein said transmission is one of an automatic transmission and a continuously variable transmission.